In a modern grinding machine, particularly one for generating an internal surface of revolutions in a workpiece, controls are provided for not only selecting the particular type of grinding cycle, i.e. the particular functions which are to take place during the grinding cycle, but also controls are provided for setting the magnitude of such parameters or functions. Such a machine, during the grinding cycle, may use functions such as LOW FEED-BACK LIMIT, HIGH FEED-BACK LIMIT, SECOND SIZE, RATE #1, RATE #2, NEW WHEEL COMPENSATION, STANDARD COMPENSATION, FIRST SIZE RETRACTION, SECOND SIZE RETRACTION, ROUGH SPARK-OUT TIME, FINISH SPARK-OUT TIME, FINISHING TIME, and LOW-FORCE TIME. In order to perform a particular grinding operation on a particular type of workpiece, an operator called a "set-up man" operates the machine and adjusts these parameters to the point where a perfect workpiece is produced. The machine is then turned over to the normal operator who may run a large number of workpieces through the machine sequentially. Each grinding cycle on a particular workpiece will be determined by the way that these parameters have been determined by the set-up man. Unfortunately, many machine operators feel that they should adjust the dials and setting for these parameters and usually this adjustment or changing of the setting eventually results in the production of poor workpieces. It is then necessary for a maintenance man or a set-up man be sent to the machine to set the machine to operate properly again. Attempts to stop the operator from changing the settings by covering the dials with doors and windows have been less than successful, since the operator (once he knows that the adjustment means is available) simply forces the doors open or breaks the machinery in order to get at the parameter adjustment means. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a grinding machine having adjustable parameter elements, and having means for rendering the adjustable parameter elements inoperative, while retaining the parameter values to which the elements have been set.
Another object of this invention is the provision of a grinding machine, which after setup, cannot have its grinding parameters changed by the operator.
A further object of the present invention is the provision of a grinding machine whose feed takes place in response to electrical pulses which pulses are controlled by logic circuitry mounted on printed circuit boards, and wherein, the insertion of a first board causes operator-controlled parameter adjustable elements to become operative and the insertion of a second circuit board renders them inoperative, but substitutes fixed elements for them.